[Expression of the gene for tetracycline resistance of plasmids R6 and RP4 in bacteria of the family Enterobacteriaceae].

It was found that manifestation of the tetracycline resistance gene depended on the type of the plasmid containing the gene. The tetracycline resistance gene was subject to less repression in plasmid R6 than in plasmid RP4. Sensitivity of the initial plasmid-free bacteria varied within lower dose ranges than that of the plasmid-carrying strains. Regulation of the tetracycline resistance gene manifestation in the given plasmid may change in different bacterial hosts, i.e. in different cytoplasmic environment at different gene background.